1. Field of the Invention
The present invention relates to a process for separating phthalimido-peroxycaproic acid (PAP) from solutions in organic solvents in which it is dissolved.
In particular the present invention relates to a process for separating phthalimido-peroxycaproic acid (PAP) from its solutions in chlorohydrocarbons used in order to prepare it, and from the solutions in the other organic solvents used for its subsequent purification.
2. Description of the Prior Art
The process for preparing PAP is known from European Patent Application No. 490,409.
According to this process, phthalimido-caproic acid (PAC) is converted into the peroxyacid, by H.sub.2 O.sub.2, in the presence of a strong acid, in a double-phase system, in the presence of an organic solvent constituted by a halogenated aliphatic chlorohydrocarbon selected from dichloromethane and trichloromethane. The resulting PAP is recovered from the organic phase by low-temperature crystallization, or solvent removal under vacuum.
PAP recovered in that way can be purified by recrystallization or stripping, using organic solvents as disclosed in Italian Patent Application No. HI92-A-000 381 (filed on Feb. 21st, 1992).
The processes which apply the usual separation methods display some disadvantages; for example, the organic solvent used are not completely recyclable, owing to the accumulation of impurities, or unavoidable losses the case of vacuum evaporation.